Feline Lower Urinary Tract Disease (FLUTD) is a general term and includes, for example, urinary stones and other causes of bladder irritation.
The most common disorder of the group is feline idiopathic cystitis (FIC). FIC involves inflammation by an unknown cause, but stress is thought to be a significant factor.
While FLUTD can include cat urinary tract infections, it’s only seldom so. If you see blood in your cat’s urine, it is most probably a sign of FLUTD, bladder stones or a urethral plug — not an infection. In dogs, blood in the urine often is a sign of an infection, but this is rarely the case in young to middle aged cats.
FLUTD is also associated with the formation of crystals and stones in the urinary tract that can cause numerous and painful ailments for your cat. Struvite and calcium oxalate stones are common stone types.
Struvite crystals in your cat’s urine can combine with mucous and form a urethral plug. The urethra is a tube that carries urine from the bladder and out of the body.
If your cat is not peeing freely, a urinary blockage may be the cause. Contact your vet immediately as this condition is urgent and could be fatal if not treated.
Sourced from Hills.com